1. Field
Example embodiments relate to a method of treating a wafer and an apparatus for fabricating a semiconductor device employing the same, and more particularly, to a method of de-chucking a wafer using a direct voltage and an alternating voltage, and an apparatus for fabricating a semiconductor device employing the same.
2. Description of Related Art
Semiconductor devices may be manufactured using various unit processes. The unit processes may include a deposition process for forming material layers such as insulating layers, conducting layers or semiconductor layers on a wafer, a photolithography/etching process for patterning the material layers, and an ion implantation process for doping impurities in predetermined regions of the wafer. The unit process may further include a thermal treating process for activating the impurities, a chemical-mechanical polishing process for planarizing surfaces of the material layers, and a cleaning process for removing contaminants remaining on the wafer on which the unit processes above are performed.
Most of the unit processes may be performed in a space separated from an outside environment. Specifically, the depositing process and the etching process may be performed within a chamber having a closed space for surrounding the wafer. In such a case, a chuck may be installed in the chamber for supporting the wafer.
In order to apply the depositing or etching process to the wafer, the wafer may be loaded on the electrostatic chuck. The electrostatic chuck may attract the wafer using an electrostatic force.
After completing the process, the wafer may be unloaded from the electrostatic chuck. In order to unload the wafer from the electrostatic chuck, an electric power applied to the electrostatic chuck may be interrupted so as to eliminate the electrostatic force between the wafer and the electrostatic chuck. However, even when the electric power to the electrostatic chuck is interrupted, the electrostatic power between the wafer and the electrostatic chuck may remain for a predetermined period of time. This is because remaining charges may exist in the wafer and the electrostatic chuck. In the case where the wafer may be physically separated from the electrostatic chuck after interrupting the electric power, the wafer may be damaged or broken due to over-bending or over-stress.
In order to improve the above process, various methods of de-chucking a wafer have been tried. For instance, a voltage applied to electrodes in an electrostatic chuck may be interrupted after completing a process on a wafer. Following the interruption, charges remaining in the electrodes and the wafer may flow out through a grounded chamber. To eliminate the charges remaining between the electrostatic chuck and the electrodes within a short period of time, a voltage having a different polarity from the polarity applied to the electrodes during the process may be applied to the electrostatic chuck. Consequently, the charges remaining in the electrodes may be neutralized such that the electrostatic power between the wafer and the electrostatic chuck may be weakened. However, even when a voltage having a different polarity from the polarity applied to the electrodes during the process is applied to the electrostatic chuck, many charges with polarity that is opposite the polarity applied to the electrodes may be generated. In other words, the electrostatic power between the electrostatic chuck and the wafer may not be completely extinguished, but may only be weakened gradually.